1. Field of the Disclosure
The present disclosure relates generally to an apparatus and method for detecting a received signal with high performance and low complexity in a multiple-input multiple-output (MIMO) system.
2. Background of the Related Art
A multiple-input multiple-output (MIMO) system may achieve large data transfer by employing a MIMO technique to an existing wireless communication system using multiple transmit antennas and multiple receive antennas for wireless data delivery. The MIMO system detects a signal received over multiple channel paths based on channel estimation information of a receiver end, and requires the signal detection have high performance and low complexity by using an efficient algorithm. Among conventional detection methods, a maximum likelihood (ML) scheme may produce optimal performance, but it is difficult to realize the ML scheme because of high algorithmic complexity. Various algorithms such as sphere decoder (SD) and K-best are alternatives, but their complexity is variable and their performance degrades in a high-order MIMO system. A fixed-complexity sphere decoder (FSD) algorithm produces a quasi-ML optimal performance with fixed complexity. However, when the number of antennas and modulation order increase, a full expansion (FE) stage for generating and expanding all of the available candidate vectors increases and thus, the complexity of the FSD algorithm rises.
To overcome the complexity drawback of MIMO detection, a conventional method inserts lattice reduction to preprocessing. The lattice reduction is used in association with a simple linear or successive interference cancellation (SIC) detector and may improve the performance with low additional complexity. However, the lattice reduction-aided algorithm combined with the linear and SIC detector may degrade in performance as the number of antennas increase. In this respect, a lattice reduction (LR) K-best combines the LR with K-best which is a tree-type algorithm. Similar to the K-best, the LR K-best requires additional computation in the sorting-process of every stage and the performance may degrade in a high-order system.